It's 1967. The Vietnam War has been raging for more than a decade. Marine Corps veteran John "Chickie" Donohue is with some buddies in a bar, toasting those who have lost their lives in combat. A challenge is floated: who will venture to Vietnam and deliver alcohol to friends still fighting overseas? Donohue decides he's going to take on that task, even if no one believes he can do it. And so starts a wild ride through dangerous war zones and embassy halls as Chickie makes it his mission to spread cheer – and beer – to troops he knows.

It sounds like a pitch for a madcap comedy, but it's a true story, as chronicled in a documentary short called The Greatest Beer Run Ever. And now it's the basis for Green Book director Peter Farrelly's latest film, which shares the title. Zac Efron plays Chickie, while the movie also stars Russell Crowe and old Farrelly friend Bill Murray.

As the trailer launched today, we talked to Farrelly about why he wanted to tackle the tale, and which actor nearly had a wee inside a fake embassy…

Stranger Than Fiction

The birth of The Greatest Beer Run Ever in movie form came when Peter Farrelly was sent the short by a friend. "I thought, ‘Wow, this is an amazing story,’" Farrelly says. "I immediately called my attorney — that’s my sister, Cindy – and said, ‘Hey, let’s try to get the right to this.’ She learned the rights were taken and they were over at Skydance and I said, ‘Hook me up, I wanna talk to ‘em about it.’ I sought it out and they had no script, they had no nothing, but they wanted to do the story so I just knew that’s what I wanted to do next." And yes, in case you were wondering he's not kidding about his sister (she also appeared in Kingpin).

Yet while he jumped on the story, Farrelly is aware that it's his second based-on-truth tale in a row after his previous film. Which, let's not forget, won three Oscars, including Best Picture… "When I thought later that it’s a true life story just like Green Book, I thought, ‘That sucks’. But I thought, ‘Whatever, I like it.’ I wish it wasn’t that! It’s not by choice, I just pick what I like and this just happened to be another true life story. I will go out of my way not to make one next." You heard it here first: Peter Farrelly's 'Unicorn Ninja Rock Monster', coming 2024!

Meet Chickie

"Chickie" Donohue is the main man in the movie, and if you were worried that the focal point of the doc has passed on, prepare to be reassured. "Chick is alive and kicking!" Farrelly laughs. "He’s 81 years old and is a spark plug. He’s got a better memory than me, I will tell you that. He could tell you every single place he’s been. He’ll talk about being in Saigon, which happened 55 years ago and he’ll say, ‘Yeah, I was walking down whatever street and hung a right on blankety street and then I came to this intersection…’ And I’ll say, ‘How the hell do you remember all this?’ He has a memory of all the names, he’s got an incredible memory about this thing. And he’s a lot of fun to be around, I love the guy."

Getting the real Chickie's approval was a benchmark for the director. "The person I want to please the most is Chickie," Farrelly continues. "If everybody loved this movie except for Chickie, I would hate it, it would be a disaster for me. I just want Chickie to look at it and say, ‘That’s how it happened,’ and by the way, that this is his reaction. He said, ‘The way I was even thinking, that’s in the movie.’ It’s really great."

Zac Fact

While Zac Efron might be looked at as a name to help get the movie made, Farrelly explains that wasn't it. And he almost didn't cast him. "I was fighting his good looks. He never takes his shirt off, that’s for sure, because the guy is like kibble. Chickie worked on ships so he was in good shape, but he’s not a pretty boy," explains the director. "The thing I liked about Zac was I met with him and Zac had an attitude of ‘I wanna do something completely different. And I’m looking to you for help. I want you to steer me in a different direction than I’ve ever done.’"

"To me he’s exactly like a young Travolta in Saturday Night Fever," Farrelly says of the character. "He’s urban, he’s a tough guy, he’s not that smart, this character. He’s foolish at times, but his heart is always in the right place. He means well and he wants to grow. And he breaks your heart."

Pay the Bill

Bill Murray plays The Colonel, owner and barkeep of Chickie's favourite watering hole and the man who challenges him to go on the beer run in the first place. Murray – who Farrelly has worked with a number of times — was the director's only choice for the character. "I always love being around Bill! This is, I think, my fifth thing with Bill," Farrelly says. "He’s a dream, I love him, he’s my favourite. And ironically, the producer, Andrew Muscato who did that short doc, he’s good friends with Bill Murray too, so getting Bill was a no-brainer. Bill is amazing in this movie. People don’t even realise it’s him at times."

Crowe-ing

Murray might be a veteran, but this is Farrelly's first time working with Russell Crowe, who plays a character composited from various war correspondents who Chickie encountered in Vietnam. The director tried to lure him for a past project, though. "Almost 20 years ago in Sydney, I was trying to convince him to do The Three Stooges and he didn’t do it, but we hung out for a couple of days and became friends," Farrelly offers. "Over the years I’ve gotten phone calls from him here and there, I’ve talked to him."

And from the sounds of it, it won't be the last time, either. "He’s so professional and will help the other cast members," says Farrelly. "They’re spending time as my assistant directors, saying, ‘Hey, try this, do that.’ So it’s unbelievably helpful and Russell was a dream. I’d never worked with him before but I met him, So we always wanted to work together and it was as good as I imagined. He was on, he was really, really sharp."

Reality bites

Scenes set in Saigon and elsewhere in Vietnam were shot in Thailand, which proved to be a challenging and fruitful experience for the director. And while Crowe was sharp, Farrelly recalls that even he was fooled by one piece of set creation. "We shot five days in front of our facade of the American embassy — it looked exactly what the embassy looked like in Saigon," explains Farrelly. "And we were doing the scenes out front. We’d been there three days and Russell said, ‘Hey, can I go in and use the bathroom?’ I said, ‘That’s a wall! It’s not real!’ ‘What?!’ He goes, ‘Oh my god, I was wondering how the hell you guys were so lucky to find a building that looks exactly like the US embassy!’

"It was definitely challenging but a phenomenal experience. I have a guy named Tim Galvin who is our production designer, and he’s a genius," Farrelly says. "He got together with Bao Tranchi, our costume designer and between the two of them, they recreated Saigon and Vietnam, everywhere."

Through the eyes of babes

A pivotal scene for both Chickie and the movie is one where he meets a young Vietnamese girl on the road. Despite his friendly overtones, Chickie realises the true horror that has been visited upon the Vietnamese during the war. "He’d come across this little girl playing with a ball and he had that thing where he was trying to say he’s a friend, an American. He saw the horror on her face and he started doing everything he could to show that was an American but that he was friendly," Farrelly outlines. "That was a moment where he started to see, ‘Wow, they don’t want us here. In fact, they’re terrified of us.’ That little girl, her name is Chananpicha Phaipa and she was incredible. We were all moved by that performance on the set because the reality of what had happened and the way she did it, this was a five-, six-year-old. For the real Chickie it was a turning point because he started to wonder what the truth was about that war."

War crimes

Despite its knockabout tone, the movie has serious issues on its mind, chronicling how both Chickie and those around him in his neighbourhood changed how they saw the war — it's something that happened in Farrelly's life, too. "I identified with where he was coming from and where he got to," he says. "This took place in 1967 and I was 10 years old. At that time, everybody in my neighbourhood were all for the war, we thought it was a good war. We hadn’t realised yet what a shit storm it was and we were all thinking, ‘This is World War II’. It took me into when I was in high school in the ‘70s where the truth started leaking out about that war and where I came fully the other way — ‘How could they have done that?’ That’s what Chickie did, only he had it in a smaller period of time. "

The Greatest Beer Run Ever will be in cinemas and on Apple TV+ from 30 September.